Joint Gap

ABSTRACT

A joint gap eliminator comprises a substantially planar gap covering strip ( 3 ) secured to formwork ( 2 ) at one side of a joint of settable material ( 8 ). The covering strip ( 3 ) extends laterally across the joint so as to be supported at the other side of the joint in a manner which allows relative movement between the other side of the joint and the covering strip ( 3 ).

This invention relates to a joint gap eliminator for use with formwork such as boundary screed rails and other leave-in-place formwork for concrete or other slabs or the like of settable material.

Where screed rails or joint formwork are used on adjacent slabs, a manufactured joint is formed. Such joints are subject to expansion and contraction movement as a result of drying, shrinkage and thermal changes, for example as a result of seasonal temperature changes.

When a movement occurs, generally initially as a result of shrinkage and subsequently as a result of thermal change, a gap occurs at the joint. This gap is a cause for concern for several reasons. The formed arises, or adjacent top edges of the joint now newly exposed, are susceptible to impact damage and chipping from vertical or like loads to be received on the joint, particularly from wheeled traffic passing across the open joint. Other causes for concern range from the possibility of a person tripping and detritus collecting in the opened gap.

Conventional practice is to fill the gap with proprietary semi-rigid compounds over a period of several visits as the size of the gap increases with time. This is a costly and time-consuming exercise.

It is therefore an object of the present invention to provide a joint gap eliminator which overcomes or at least ameliorates the above-described problems.

According to the present invention there is provided a joint gap eliminator comprising a substantially planar gap covering strip secured to formwork at one side of a joint of settable material and extending laterally across the joint so as to be supported at the other side of the joint in a manner which allows relative movement between the other side of the joint and the covering strip.

The covering strip may be provided with a plurality of apertures to permit the passage of air therethrough.

An upright strip may be adapted to be secured in settable material at the other side of the joint. A step may be formed in the upper surface of the settable material at the upright strip so as to accommodate the covering strip.

The upright strip may be secured to formwork at the other side of the joint, for example by a plurality of lateral spacers. The lateral spacers may be substantially U-shaped. The spacers may be secured to the upright strip and to the formwork. The spacers may be provided with apertures for keying with the settable material. The spacers may serve to support the lower surface of the covering strip on the other side of the joint.

Alternatively, the upright strip may be connected to a support member which may include a substantially horizontal portion adapted to support the covering strip. The substantially horizontal portion of the support member may be provided with a plurality of apertures for the passage of air therethrough. The support member may include a downwardly extending portion, spaced from the upright strip, adapted to protect a face of a slab of settable material. The upright strip may be provided with a plurality of apertures, for example in a lower edge thereof.

The formwork may comprise at least one screed rail.

The present invention also relates to a joint gap eliminator system including a joint gap eliminator as hereinbefore defined and formwork positioned at least at one side of a joint of settable material.

For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying drawings in which:

FIG. 1 is a diagrammatic perspective view of one embodiment of a joint gap eliminator according to the present invention mounted onto a pair of adjacent screed rails;

FIG. 2 shows the joint gap eliminator of FIG. 1 in a partly disassembled state to show a gap-covering strip;

FIG. 3 shows the joint gap eliminator of FIG. 1 in an alternative partly disassembled state;

FIG. 4 is a diagrammatic cross-sectional view of the assembly shown in FIG. 1;

FIG. 5 is a diagrammatic cross-sectional view of the assembly of FIG. 1 within adjacent concrete slabs, without a joint gap having opened;

FIG. 6 is a diagrammatic cross-sectional view corresponding to FIG. 5, but after a joint gap has opened;

FIG. 7 shows the assembly of FIG. 6 in use;

FIG. 8 is a diagrammatic perspective view of another embodiment of a joint gap eliminator according to the present invention mounted on a screed rail;

FIG. 9 shows the joint gap eliminator of FIG. 8 in a partly disassembled state to show a gap-covering strip;

FIG. 10 shows the joint gap eliminator of FIG. 8 in an alternative partly disassembled state;

FIG. 11 is a diagrammatic cross-sectional view showing the assembly of FIG. 8 within adjacent concrete slabs, without a joint gap having opened; and

FIG. 12 is a diagrammatic cross-sectional view corresponding to FIG. 11, but after a joint gap has opened.

FIGS. 1 to 7 show a joint gap eliminator 1 mounted on adjacent screed rails 2, such as those available from Amicitia UK Limited under the trade name METAFORM, which are conventionally used to form joints between adjacent slabs of cast concrete or the like. The joint gap eliminator includes a substantially horizontal gap-covering strip 3, for example of steel or similar material, a substantially vertical slab edge strip 4, and a plurality of connecting support members 5.

The gap-covering strip 3 is generally planar and rectangular in configuration and has a width sufficient to cover the tops of the two screed rails 2 and to extend laterally beyond the top of one of the screed rails. The strip 3 is secured to the top of one of the screed rails by any suitable means, such as by welding, although other securing means, such as fasteners or adhesive may be used if desired. The lateral extension of the strip 3 passes freely over and beyond the other of the screed rails. The strip 3 is provided with a plurality of apertures 6, such as circular holes or elongate slots, to allow the escape of any air which may be trapped beneath the strip. The gap-covering strip is best shown in FIG. 2, but FIG. 2 also shows the edge strip 4 and support members 5 secured to the other screed rail.

The vertical slab edge strip 4 and the support members 5 are secured together to form an integral component which is secured to the other of the screed rails 2, for example by welding or other suitable fastening means. The edge strip 4 is in practice an upright rectangular strip of material, while the support members 5 are generally U-shaped in configuration with a leg at each end extending from a generally planar base which extends in an upright direction to the top of the concrete 8. In this way, the cover strip 3 is supported on the top edges of the support members 5. A step is formed in the upper surface of the concrete at the edge strip 4, with the upper surface of the concrete beneath the covering strip 3 being at a slightly lower level so as to accommodate the thickness of the covering strip. The vertical extent of the edge strip 4 may be selected in dependence on the expected load and/or on the nature of the proposed usage of the joint gap eliminator. The number and spacing of the support members 5 may be selected in dependence upon the expected load and/or on environmental requirements. The support members 5 are provided with an aperture 7 which facilitates bonding or keying with a concrete slab. The support members 5 are positioned at an elevation corresponding to the level of the concrete at the lower level of the step. In this way, the upper edge of the support members 5 also serves to support the underside of the covering strip 3. The support members 5 ensure the free edge of the edge strip 4 is spaced laterally from the other screed rail by a distance corresponding to the lateral extension of the gap-covering strip 3 such that, when a joint is first formed, the free edge of the edge strip 4 substantially abuts the lateral edge of the gap-covering strip 3 as shown in FIG. 4 and, more particularly, in FIG. 5 where the screed rails 2 and the edge strip 4 and support members 5 are shown embedded in adjacent concrete slabs 8 which are poured once the screed rails and the gap eliminator have been fully configured. The edge strip 4 and support members 5 are best shown in FIG. 3.

The joint gap eliminator 1 is elongate and can be provided in predetermined lengths which can be joined together or cut as required, for example to suit the length of the screed rails or other formwork. The width of the gap-covering strip 3 and the length of the support members 5 may be selected according to the width of the gap expected to be required to be covered.

As can be seen from the figures, and especially from FIGS. 6 and 7, the joint gap eliminator provides effective protection for a joint gap between two slabs with the gap-covering strip able to move relative to one of the screed rails and slabs whilst covering the gap between the adjacent screed rails and slabs. FIG. 7 shows a wheel 9 of a vehicle or the like passing over the joint gap eliminator. The previous gap which extended the entire depth of the slabs is transformed into a shallow gap located on the top of one of the cast slabs, with the strip 3 covering the previous gap, the shallow gap being supported in effect by substantially the entire thickness of the slab. There is, therefore, no need to fill the previous gap with proprietary filling material. The gap eliminator also permits relative movement between the slabs 8 and the screed rails 2, allowing the width of the gap to increase and decrease, while still fully protecting the arises, or adjacent top edges, of the joint against impact damage and spalling.

Various modifications may be made without departing from the scope of the present invention. For example, timber formwork could be used for mounting the joint gap eliminator into the required position, or the gap-covering strip, at least, may be made of a more decorative material, such as brass.

FIGS. 8 to 12 show an alternative joint gap eliminator assembly and the same references are used to denote the same or similar parts. A joint gap eliminator 1 is mounted on a single screed rail 2 and includes a substantially horizontal gap-covering strip 3 and a substantially vertical slab edge strip 4 including a lateral support member 11.

The gap-covering strip 3 is generally planar and rectangular in configuration and has a width sufficient to cover the top of the screed rail 2 and to extend laterally beyond the top of the screed rail over an adjoining concrete slab as will be described in more detail hereinafter. The strip 3 is secured to the top of the screed rail by any suitable means, such as by welding, although other securing means, such as fasteners or adhesive may be used if desired. The strip 3 is provided with a plurality of apertures 6, such as circular holes or elongate slots, to allow the escape of any air which may be trapped beneath the strip. The gap-covering strip is best shown in FIG. 2, but FIG. 2 also shows the edge strip 4 and support member 11.

The vertical slab edge strip 4 and the support member 11 are formed as an integral component having a substantially Z-shaped cross-section. The edge strip 4 is in the form of an upright rectangular strip of material which extends to a level corresponding to the top of the concrete slab 8, while the support member 11 initially extends in an inclined direction upwardly and away from the lower edge of the strip 4 to a level below the top of the strip 4 corresponding substantially to the thickness of the gap-covering strip 3. The support member 11 then extends substantially horizontally to the edge of the concrete slab 8 and then extends substantially vertically downwards to cover a portion of the upright edge of the concrete to protect the edge of the concrete slab 8. In this way, the cover strip 3 is supported on the horizontal top surface of the support member 11. A step is formed in the upper surface of the concrete at the edge strip 4, with the upper surface of the concrete beneath the covering strip 3 being at a slightly lower level so as to accommodate the thickness of the covering strip. The vertical extent of the edge strip 4 may be selected in dependence on the expected load and/or on the nature of the proposed usage of the joint gap eliminator. The horizontal portion of the support member 11 and the lower edge of the edge strip 4 are provided with apertures 13 and 15 which facilitates bonding or keying with a concrete slab. The support member 11 is positioned at an elevation corresponding to the level of the concrete at the lower level of the step. In this way, the horizontal top surface of the support member 11 also serves to support the underside of the covering strip 3. The support member 11 ensures the free edge of the edge strip 4 is spaced laterally from the other screed rail by a distance corresponding to the lateral extension of the gap-covering strip 3 such that, when a joint is first formed, the free edge of the edge strip 4 substantially abuts the lateral edge of the gap-covering strip 3 as shown in FIG. 11 where the screed rail 2 and the edge strip 4 and support member 11 are shown embedded in adjacent concrete slabs 8 which are poured once the screed rail and the gap eliminator have been fully configured.

The joint gap eliminator 1 is elongate and can be provided in predetermined lengths which can be joined together or cut as required, for example to suit the length of the screed rails or other formwork. The width of the gap-covering strip 3 and the width of the support member 11 may be selected according to the width of the gap expected to be required to be covered.

As can be seen from FIGS. 11 and 12, the joint gap eliminator provides effective protection for a joint gap between two slabs with the gap-covering strip able to move relative to one of the slabs whilst covering the gap between the adjacent slabs. The previous gap which extended the entire depth of the slabs is transformed into a shallow gap located on the top of one of the cast slabs, with the strip 3 covering the previous gap, the shallow gap being supported in effect by substantially the entire thickness of the slab. There is, therefore, no need to fill the previous gap with proprietary filling material. The gap eliminator also permits relative movement between the slabs 8, allowing the width of the gap to increase and decrease, while still fully protecting the arises, or adjacent top edges, of the joint against impact damage and spalling. 

1. A joint gap eliminator comprising a substantially planar gap covering strip (3) secured to formwork (2) at one side of a joint of settable material (8) and extending laterally across the joint so as to be supported at the other side of the joint in a manner which allows relative movement between the other side of the joint and the covering strip (3).
 2. A joint gap eliminator as claimed in claim 1, wherein the covering strip (3) is provided with a plurality of apertures (6) to permit the passage of air therethrough.
 3. A joint gap eliminator as claimed in claim 1, wherein an upright strip (4) is adapted to be secured in settable material (8) at the other side of the joint.
 4. A joint gap eliminator as claimed in claim 3, wherein a step is formed in the upper surface of the settable material at the upright strip (4) so as to accommodate the covering strip (3).
 5. A joint gap eliminator as claimed in claim 3, wherein the upright strip (4) is secured to formwork (2) at the other side of the joint.
 6. A joint gap eliminator as claimed in claim 5, wherein the upright strip (4) is secure to the formwork (2) by a plurality of lateral spacers (5).
 7. A joint gap eliminator as claimed in claim 6, wherein the lateral spacers (5) are substantially U-shaped.
 8. A joint gap eliminator as claimed in claim 6, wherein the spacers (5) are secured to the upright strip (4) and to the formwork (2).
 9. A joint gap eliminator as claimed in claim 6, wherein the spacers (5) are provided with apertures (7) for keying with the settable material (8).
 10. A joint gap eliminator as claimed in claim 6, wherein the spacers (5) serve to support the lower surface of the covering strip (3) on the other side of the joint.
 11. A joint gap eliminator as claimed in claim 3, wherein the upright strip (4) is connected to a support member (11).
 12. A joint gap eliminator as claimed in claim 11, wherein the support member (11) includes a substantially horizontal portion adapted to support the covering strip (3).
 13. A joint gap eliminator as claimed in claim 12, wherein the substantially horizontal portion of the support member (11) is provided with a plurality of apertures (13) to permit the passage of air therethrough.
 14. A joint gap eliminator as claimed in claim 12, wherein the support member (11) includes a downwardly extending portion adapted to protect a face of a slab of settable material (8).
 15. A joint gap eliminator as claimed in claim 11, wherein the upright strip (4) is provided with a plurality of apertures (15).
 16. A joint gap eliminator as claimed in claim 15, wherein the apertures (15) are formed in a lower edge of the upright strip (4).
 17. A joint gap eliminator as claimed in claim 1, wherein the formwork (2) comprises at least one screed rail.
 18. A joint gap eliminator system including a joint gap eliminator as claimed in claim 1, and formwork (2) positioned at least at one side of a joint of settable material (8). 